News; 50 killed at gay nightclub in Florida; Attack is deadliest mass shooting in U.S.

ORLANDO, FLORIDA U.S  -- The massacre at an Orlando nightclub that claimed 50 lives is the worst mass shooting in U.S. history.

Police Chief John Mina confirmed at a news conference Sunday morning that 50 people were killed, up from 20 as earlier reported.

Mayor Buddy Dyer says 53 more are hospitalized after the early Sunday incident. He says the shooter is among the dead. He also says the shooter used an assault rifle on all those dead. Officials say one officer was shot, and has injuries to his face.

Earlier, U.S. Rep. Alan Grayson identified the shooter as Omar Mateen of Port St. Lucie, Florida. He cited law enforcement officials in speaking to reporters.

Officials also have said they're investigating whether the incident was an act of terrorism.